Someone stole my phone help? Read Below?

alright so today was like any other normal but at the end of the day at school my phone wasn't in my locker my friend i guess you coudl call her a friend knows my combination so i think it could be her but at our school they don't change the combination so i could be a 7th grader or 8th grader. i know i had my phone because i cheek my phone during passing period earlier that day. and our lockers are like this http://www.google.com/imgres?imgurl=http://grover.mirc.gatech.edu/floorplan/images/lockers.jpg&imgrefurl=http://grover.mirc.gatech.edu/floorplan/floorplan.php%3Fitem%3D4%26location%3Dgowning1&usg=__o_by3-vuTmNeTC3oxhiIikLFqbE=&h=768&w=1024&sz=71&hl=en&start=0&zoom=1&tbnid=nJFFFdK1W0hReM:&tbnh=120&tbnw=160&ei=jyGmTey-I6jW0QHq1IjlCA&prev=/images%3Fq%3Dlockers%26um%3D1%26hl%3Den%26client%3Dfirefox-a%26sa%3DN%26rls%3Dorg.mozilla:en-US:official%26biw%3D1366%26bih%3D564%26tbm%3Disch&um=1&itbs=1&iact=hc&vpx=1016&vpy=263&dur=1814&hovh=194&hovw=259&tx=115&ty=100&oei=jyGmTey-I6jW0QHq1IjlCA&page=1&ndsp=28&ved=1t:429,r:26,s:0 and i didnt lock the lock up all the way to lock my locker because after class my lock was upside down so someone could have went in my lock and took my phone i dont know what to do please help! (i dont take my phone to my classes either)...